Wound therapy system and related methods therefor

ABSTRACT

A portable system for subatmospheric pressure therapy in connection with healing a surgical wound, including a wound dressing dimensioned for positioning relative to a wound bed of a subject and a subatmospheric pressure mechanism dimensioned to be carried or worn by the subject. The subatmospheric pressure mechanism includes a housing having a control unit adapted to draw a vacuum and a canister associated with the housing. The canister has a collection bag disposed therein, which is in fluid communication with the wound dressing to receive exudates from the wound bed. The collection bag is adapted to expand upon receipt of the fluids and has means to release gas from within the collection bag in connection with operation of the control unit. With this arrangement, the canister is attitude independent, i.e., the canister may be positioned on edge, on its side or on its end etc. while still maintaining operation of the control unit. The collection bag may include a hydrophobic vent or material for releasing the gases. In another embodiment, the collection bag comprises a gas permeable material. The collection bag may include one of pleats or bellows.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims the benefit under 35 U.S.C. 120 to co-pending U.S. patent application Ser. No. 12/124,707, titled WOUND THERAPY SYSTEM WITH PORTABLE CONTAINER APPARATUS, which was filed on May 21, 2008, the entirety of which is hereby incorporated by reference for all purposes.

BACKGROUND

1. Technical Field

The present disclosure relates to treating an open wound, and, more specifically, relates to a sub-atmospheric wound therapy system including a portable container adapted to maintain the operation of the system regardless of the orientation or positioning of the container.

2. Background of Related Art

Wound closure involves the migration of epithelial and subcutaneous tissue adjacent the wound towards the center and away from the base of the wound until the wound closes. Unfortunately, closure is difficult with large wounds, chronic wounds or wounds that have become infected. In such wounds, a zone of stasis (i.e. an area in which localized swelling of tissue restricts the flow of blood to the tissues) forms near the surface of the wound. Without sufficient blood flow, the epithelial and subcutaneous tissues surrounding the wound not only receive diminished oxygen and nutrients, but, are also less able to successfully fight microbial infection and, thus, are less able to close the wound naturally. Such wounds have presented difficulties to medical personnel for many years.

Negative pressure therapy also known as suction or vacuum therapy has been used in treating and healing wounds. Application of negative pressure, e.g. reduced or subatmospheric pressure, to a localized reservoir over a wound has been found to assist in closing the wound by promoting blood flow to the area, stimulating the formation of granulation tissue, and encouraging the migration of healthy tissue over the wound. Negative pressure may also inhibit bacterial growth by drawing fluids from the wound such as exudates, which may tend to harbor bacteria. This technique has proven particularly effective for chronic or healing-resistant wounds, and is also used for other purposes such as post-operative wound care.

Generally, negative pressure therapy provides for a wound to be covered to facilitate suction at the wound area. A conduit is introduced through the wound covering to provide fluid communication to an external vacuum source. Atmospheric gas, wound exudates, or other fluids may thus be drawn from the reservoir through the fluid conduit to stimulate healing of the wound. Exudates drawn from the reservoir may be deposited in a collection canister or container.

The systems generally require that the container is maintained in a standing or upright position such that the fluid receiving reservoir within the respective unit may be vented and continue to receive fluid from the patient until the reservoir is full. Accidental tipping or tilting of the bag and/or container may cause the suction to/from the unit to be to be shut-off prior to the fluid receiving reservoir completely filling. This problem is further exaggerated in portable units which may be worn or carried by the subject.

SUMMARY

A portable system for subatmospheric pressure therapy in connection with healing a surgical wound includes a wound dressing dimensioned for positioning relative to a wound bed of a subject and a subatmospheric pressure mechanism dimensioned to be carried or worn by the subject. The subatmospheric pressure mechanism includes a housing having a control unit adapted to draw a vacuum and a canister associated with the housing. The canister has a collection bag disposed therein, which is in fluid communication with the wound dressing to receive exudates from the wound bed. The collection bag is adapted to expand upon receipt of the fluids and has means to release gas from within the collection bag in connection with operation of the control unit. With this arrangement, the canister is attitude independent, i.e., the canister may be positioned on edge, on its side or on its end etc. while still maintaining operation of the control unit. The collection bag may include a hydrophobic vent or material for releasing the gases. In another embodiment, the collection bag comprises a gas permeable material. The collection bag may include one of pleats or bellows.

In another embodiment, the portable system for subatmospheric pressure therapy in connection with healing a surgical wound includes a wound dressing dimensioned for positioning relative to a wound bed of a subject and a subatmospheric pressure mechanism dimensioned to be carried or worn by the subject. The subatmospheric pressure mechanism includes a housing having a control unit adapted to draw a vacuum, a container defining an internal chamber in fluid communication with the vacuum and the wound dressing to receive the wound exudates, a plunger received within the internal chamber and movable during actuation of the control unit and a hydrophobic filter associated with the plunger and permitting escape of gas from the container.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein:

FIG. 1 is a side view in partial cross-section of the portable wound therapy system of the present disclosure illustrating the wound dressing and the subatmospheric pressure mechanism;

FIG. 2 is a schematic view illustrating the components of the control unit of the subatmospheric pressure mechanism;

FIG. 3 is a partial cut-away perspective view of an embodiment of a collection canister according to the present disclosure;

FIG. 4 is a cross-sectional side view of an embodiment of an expandable collection bag according to the present disclosure;

FIG. 5 is a perspective side view of another embodiment of an expandable collection bag according to the present disclosure;

FIG. 6 is a perspective side view of yet another embodiment of an expandable collection bag according to the present disclosure;

FIG. 7 is a perspective side view of still another embodiment of an expandable collection bag according to the present disclosure;

FIG. 8 is an interior perspective view of another embodiment of a collection canister according to the present disclosure;

FIG. 9 is an interior perspective view of yet another embodiment of a collection canister according to the present disclosure;

FIG. 10A is a cross-sectional side view of still another embodiment of a collection device according to the present disclosure; and

FIG. 10B is a side view of an intake mechanism of the collection device of FIG. 10A.

DETAILED DESCRIPTION

The wound therapy system of the present disclosure promotes healing of a wound via the use of a wound dressing and a portable subatmospheric pressure mechanism. Generally, the portable subatmospheric pressure mechanism applies subatmospheric pressure to the wound to effectively remove wound fluids or exudates captured by the composite wound dressing, and to increase blood flow to the wound bed and enhance cellular stimulation of epithelial and subcutaneous tissue. The wound therapy system is entirely portable, i.e., it may be worn or carried by the subject such that the subject may be completely ambulatory during the therapy period. The wound therapy system including the subatmospheric pressure mechanism and components thereof may be entirely disposable after a predetermined period of use or may be individually disposable whereby some of the components are reused for a subsequent therapy application.

The wound therapy system of the present disclosure promotes healing of a wound in conjunction with subatmospheric negative pressure therapy. The system may incorporate a variety of wound dressings, subatmospheric pressure sources and pumps, and collection canisters. The attached figures illustrate exemplary embodiments of the present disclosure and are referenced to describe the embodiments depicted therein. Hereinafter, the disclosure will be described by explaining the figures wherein like reference numerals represent like parts throughout the several views.

Referring initially to FIG. 1, wound therapy system 100 according to the present disclosure is illustrated. Wound therapy system 100 includes composite wound dressing 102 and subatmospheric pressure mechanism 104 in fluid communication with the wound dressing 102 through conduit, identified schematically as reference numeral 106.

Wound dressing 102 may includes several components, namely, wound contact layer or member 108, a wound packing member or filler 110 supported by the contact member 108 and outer layer or cover member 112. Wound contact member 108 is adapted to substantially conform to the topography of a wound bed “W”. Wound contact member 108 is substantially porous or perforated to permit exudates to pass from the wound bed “W” through the wound contact member 108. The passage of wound exudates through the wound contact member 108 may be unidirectional such that wound exudates do not flow back to the wound bed “W”. Unidirectional flow may be encouraged by directional apertures formed in contact member 108 or a lamination of materials having absorption properties differing from those of contact member 108. A non-adherent material may be selected such that contact member 108 does not tend to cling to wound bed “W” or surrounding material when it is removed. One exemplary material that may be used as a contact member 108 is sold under the trademark XEROFLOW® by Tyco Healthcare Group LP (d/b/a Covidien).

Wound packing member 110 of wound dressing 102 is intended to absorb and transfer wound fluid and exudates. Wound packing member 110 is conformable to assume the shape of any wound bed “W”. Wound packing member 110 may be treated with agents such as polyhexamethylene biguanide (PHMB) to decrease the incidence of infection, or other medicants to promote healing of the wound. A suitable wound packing material 110 is the antimicrobial dressing sold under the trademark KERLEX® AMD by Tyco Healthcare Group LP (d/b/a Covidien).

Outer member or wound covering 112 encompasses the perimeter of the wound dressing 102 to surround wound bed “W” and to provide a liquid-tight seal around the perimeter “P” of the wound bed “W”. For instance, the sealing mechanism may be any biocompatible adhesive bonded to the perimeter of wound covering 112. Thus, wound covering 112 may act as both a microbial barrier and a fluid barrier to prevent contaminants from entering wound bed “W” and for maintaining the integrity thereof.

Wound covering 112 is typically a flexible material, e.g., resilient or elastomeric, that seals the top of wound dressing 102 to prevent passage of liquids or contamination to and from the wound dressing 102. Wound covering 112 may be formed from a moisture vapor permeable membrane to promote the exchange of oxygen moisture between the wound bed “W” and the atmosphere. A membrane that provides a sufficient moisture vapor transmission rate is a transparent membrane sold under the trade name POLYSKIN® II by Tyco Healthcare Group LP (d/b/a Covidien). A transparent membrane permits an assessment of wound conditions to be made without requiring removal of the wound covering 112. Alternatively, wound covering 112 may comprise an impermeable membrane or a substantially rigid membrane.

Wound covering 112 may include a port or connector 107 in fluid communication with the interior of wound dressing 102 to facilitate connection of wound dressing 102 to conduit or tubing 106. Conduit 106 defines a fluid flow path leading through wound therapy system 100. Connector 107 may be configured as a rigid or flexible, low-profile component, and may be adapted to receive conduit 106 in a releasable and fluid tight manner. A hollow interior of connector 107 provides fluid communication between conduit 106 and the interior of wound dressing 102. Connector 107 may have a valve 109 built therein, e.g., a one-way valve to permit exudates to flow in one direction only, i.e., away from wound dressing 102 toward subatmospheric pressure mechanism 104. Connector 107 may be provided as a pre-affixed component of wound dressing 102, as a component of conduit 106, or entirely separate and connected thereto by conventional means. Alternatively, connector 107 may be eliminated if other provisions are made for providing fluid communication between wound dressing 102 and conduit 106.

Conduit 106 extends from subatmospheric pressure mechanism 104 to provide fluid communication between the interior of the wound dressing 102 and vacuum source 118. Any suitable conduit may be used including those fabricated from flexible elastomeric or polymeric materials. Conduit 106 may connect to vacuum source 118 or other system components by conventional air tight means such as friction fit, bayonet coupling, or barbed connectors. The conduit connections may be made permanent, or alternatively a quick-disconnect or other releasable means may be used to provide some adjustment flexibility to the apparatus.

Referring now to the schematic diagram of FIG. 2, in conjunction with FIG. 1, control unit 116 of subatmospheric pressure mechanism 104 will be discussed. Control unit 116 includes vacuum source or pump 118 disposed within housing 117, actuator or motor 120 disposed within housing 117 for activating the vacuum source 118 and power source 122 mounted relative to housing 117. Vacuum source or pump 118 generates or otherwise provides negative pressure to wound therapy system 100. Vacuum source or pump 118 may be a pump of the diaphragmatic, peristaltic or bellows type or the like, in which the moving part(s) draw exudates out of the wound bed “W” into the wound dressing 102 by creating areas or zones of decreased pressure e.g., vacuum zones with the wound dressing 100. This area of decreased pressure preferably communicates with the wound bed “W” to facilitate removal of the fluids therefrom and into the absorbent or non-absorbent packing member 110. One suitable peristaltic pump is the Kangaroo Enteral Pump manufactured by Tyco Healthcare Group LP (d/b/a Covidien).

Vacuum source or pump 118 may be a miniature pump or micropump that is biocompatible and adapted to maintain or draw adequate and therapeutic vacuum levels. The vacuum level of subatmospheric pressure achieved may be in the range of about 20 mmHg to about 500 mgHg. In some embodiments, about 75 mmHg and about 125 mmHg is desired or between about 35 mmHg and 75 mmHg may be desired. Vacuum source or pump 118 is actuated by actuator 120 which may be any means known by those skilled in the art, including, for example, AC motors, DC motors, voice coil actuators, solenoids, etc. Actuator 120 may be incorporated within pump 118.

On an exhaust side of vacuum source 118 fluid conduit 106 connects vacuum source 118 to collection canister 132. Conduit 106 may comprise the same material or construction along the entire length of the tubing or may assume an alternate form between vacuum source 118 and canister 132 than between wound dressing 102 and vacuum source 118. In the alternative, it may be separate tubing.

Power source 122 may be disposed within housing 117 or separately mountable to the housing 117. A suitable power source 122 includes alkaline batteries, wet cell batteries, dry cell batteries, nickel cadmium batteries, solar generated means, lithium batteries, NiMH batteries (nickel metal hydride) each of which may be of the disposable or rechargeable variety.

Referring again to FIG. 1, subatmospheric pressure mechanism 104 includes collection canister 132 which collects the exudates removed from the wound bed “W” during therapy through conduit, or tubing, 106. Collection canister 132 is releasably connected to housing 117 of control unit 116. Collection canister 132 may comprise any container suitable for containing wound fluids and is substantially rigid defining an internal chamber 133 in fluid communication with tubing 106. Collection canister 132 may contain an absorbent material to consolidate or contain the wound drainage or debris. In embodiments, at least a portion of collection canister 132 may be transparent to assist in evaluating the color, quality, or quantity of wound exudates. A transparent canister may thus assist in determining the remaining capacity of canister 132 or when the canister 132 should be replaced. In the alternative, collection canister 132 may be relatively flexible.

Turning now to FIG. 3, an embodiment of a collection canister according to the present disclosure is shown generally as collection canister 232. Collection canister 232 includes a substantially rigid housing 204 defining a chamber 204 a for receiving a collection bag 202. A cover 206 is configured to engage container 204 to for a sealed chamber 204 a. Alternatively, cover 206 may be integrally formed with housing 117. Cover 206 defines an inlet port 206 a and an outlet port 206 b. Inlet port 206 a is in fluid communication with wound dressing 102 and is configured to receive fluid “F” or exudates therefrom. A check valve 212 may be integrally formed with cover 206. Outlet port 206 b is operably connected to vacuum source or pump 118. Outlet port 206 includes an extension 207. Extension 207 extends within chamber 204 a of container 204. Extension 207 includes a channel 207 a or other suitable configuration to ensure suction continues to be provided to chamber 204 a as collection bag 202 expands to fill chamber 204 a.

Collection bag 202 includes an expandable cavity 202 a configured for receiving fluid “F”. Collection bag 202 is constructed with a hydrophobic membrane or other suitable material capable of permitting gases to escape cavity 202 a. Alternatively, collection bag 202 may have a hydrophobic vent (not shown). Collection bag 202 is maintained in fluid communication with inlet port 206 a. It is envisioned that collection bag 202 may be integrally formed with cover 206.

In operation, suction from pump 118 is provided to chamber 204 a of container 204 through outlet port 206 b. As a vacuum builds within chamber 204 a suction is provided to wound dressing 102 to draw fluid “F” from wound “W”. As fluid “F” flows from wound “W” through inlet port 206 a into cavity 202 a of collection bag 202, any residual air or other gases in the system pass through collection bag 202. Cavity 202 a expands to accommodate fluid “F” as the flow into collection bag 202 continues. Check valve 212 prevents fluid “F” from flowing from cavity 202 a back towards wound dressing 102. Alternatively, check valve 212 may be formed on a distal end 106 b of conduit 106. Collection bag 202 continues to expand as fluid “F” is drawn from wound “W”. Channel 207 a formed in extension 207 of outlet port 206 b is configured to permit the continued flow of suction into chamber 204 a, thereby allowing collection bag 202 to expand to fill chamber 204 a. Once collection bag 202 and/or chamber 204 a is filled, cover 206 may be removed and collection bag 202 may be emptied and/or replaced.

With reference now to FIG. 4, an alternate embodiment of a collection bag for use in collection canister 232 is shown as collection bag 202′. Collection bag 202′ defines an expandable cavity 202 a′ for receiving fluids. A sealing band 204′ maintains collection bag 202′ in a sealed relationship with patient tube with inlet port 206 a of cover 206. A check valve 212′ is positioned on a distal end 106 b of a conduit 106 to prevent back flow of fluid from collection bag 202′ into conduit 106.

Collection bag 202′ includes a bulb-shaped container constructed of rubber, polymer or other expandable material. As noted above, collection bag 202′ defines an expandable cavity 202 a′. Collection bag 202′ further includes a hydrophobic plug 203′ for releasing gas from within cavity 202 a′. As fluid “F” flows from conduit 106 through check valve 212′ and into cavity 202 a′ of collection bag 202′, collection bag 202′ expands to accommodate the additional fluid. Any gas trapped within cavity 202 a′ may be vented through hydrophobic plug 203′. Collection bag 202′ may be removed from conduit 106 and discarded as necessary. It is envisioned that collection bag 202′ may be reused. Collection bag 202′ may optionally include a tie, draw string or other suitable closure device for sealing cavity 202 a′.

Turning to FIG. 5, an alternate embodiment of a collection bag of the present disclosure is shown generally as collection bag 302. Collection bag 302 includes a pleated container constructed of a hydrophobic material, e.g. TYVEK. This construction permits any air or other gases trapped with the collection system to pass through collection bag 302 while collecting fluid “F” (FIG. 3) therein. Collection bag 302 defines an expandable cavity 302 a for receiving fluids. In one embodiment, collection bag 302 is preferably configured to expand to fill chamber 204 a of collection canister 232. Collection bag 302 may further include a window 303 for viewing the contents of cavity 302 a. As fluid enters cavity 302 a of collection bag 302, pleats 301 formed in collection bag 302 expand to increase the capacity of cavity 302 a and accommodate the additional fluid.

With reference now to FIG. 6, another embodiment of a collection bag of the present disclosure is shown as collection bag 402. Collection bag 402 is constructed of hydrophobic material and includes accordion-like folds 401. Folds 401 are configured to expand as collection bag 402 fills with fluid “F” (FIG. 3).

Turning now to FIG. 7, yet another embodiment of a collection bag is shown generally as collection bag 502. Collection bag 502 is constructed from hydrophobic material that is rolled. Collection bag 502 may include a window (not shown) for viewing the contents therein.

Turning now to FIG. 8, another embodiment of the present disclosure is shown generally as collection device 600. Collection device 600 includes a container 604 defining a first chamber 606 in fluid communication with a second chamber 608 separated by a divider 607. Container 604 further includes an inlet port 604 a in fluid communication with first chamber 606 and one or more outlet ports 604 b in fluid communication with the second chamber 608. Inlet port 604 a is operably connected to conduit 106′. Conduit 106′ may include a check valve (not shown). Outlet ports 604 b are operably connected to a source of suction not shown.

A plunger 610 is retained within second chamber 608 of container 604. Plunger 610 is a substantially planar member including a hydrophobic membrane 612 and a seal 214 a extending about a perimeter 214 of plunger 610. Plunger 610 is configured to be advanced in the direction of arrow A as suction is applied to outlet ports 604 b and air is removed from within second chamber 608. Alternatively, it is envisioned that plunger 610 may be attached to an advancement mechanism, including hydraulic, pneumatic and motorized cylinder, for advancing plunger 610. Movement of plunger 610 towards outlets 604 b (direction of arrow “A”) creates a vacuum in first chamber 606. The vacuum created in first chamber 606 provides suction to conduit 106′. As plunger 610 is drawn towards outlets 604 b fluid “F” fills first and second chamber 606, 608. Residual air trapped within container 604 and/or conduit 106′ is exhausted though hydrophobic membrane 612. Once first and second chambers 606, 608 are filled, conduit 106′ is disconnected from container 604. Collection device 600 may include a valve or other mechanism (not shown) for draining container 604. Alternatively, collection device 600 may be discarded.

Turning now to FIG. 9, another embodiment of the present disclosure is shown generally as collection device 700. Collection device 700 is substantially similar to collection device 600 and includes a container 704 having a first chamber 706 in fluid communication with a second chamber 708. First and second chambers 706, 708 are separated by a divider. An inlet port 704 a fluidly communicates conduit 106′ with first chamber 706. An outlet port 704 b fluidly communicates second chamber 708 with a vacuum source (not shown). A plunger 710 is received within first chamber 706. Plunger 710 includes a hydrophobic membrane 212. Plunger 710 is configured to create a vacuum in first chamber 706 as plunger 710 is advanced in the direction of arrow “B”. The vacuum in first chamber 706 causes fluid “F” to be drawn through conduit 106′. Once first chamber 706 is filled, conduit 106′ is disconnected from container 704. Collection device 700 may include a valve or other mechanism (not shown) for draining container 704. Alternatively, collection device 700 may be discarded.

With reference now to FIGS. 10A and 10B, an alternate embodiment of the present disclosure is shown generally as collection canister 800. Collection device 800 includes a container 804 having a cover 806 and defining a substantially sealed chamber container 804 a. An inlet port (not shown) may be formed in container 804 and/or cover 806. Cover 806 further includes an outlet port 806 b configured for operable connection with a vacuum source. Cover 806 further includes a flange 807 extending inwardly from outlet port 806 b. An intake mechanism 810 extends from flange 807 and is in fluid communication with outlet port 806 b.

Intake mechanism 810 includes a bellows 812 and a float 814. Bellows 812 may be constructed of silicone or other suitable flexible material. Bellows 812 defines a passageway 812 therethrough in fluid communication with outlet port 806 b. Bellows 812 includes openings 813 for receiving air from with chamber 804 a. Float 814 may include an air bag, open cell material or other suitable material with a low mass. Float 814 may be affixed to an end of bellows 812. Alternatively, float 814 may be over-molded to bellows 812. Float 814 is configured to maintain at least one of openings 813 formed in bellows 812 above the level of fluid “F” as chamber 804 a fills with fluid “F”. Bellows 812 and float 814 are configured such that as container 804 is transported, i.e. tilted or inverted, collection device 800 continues to collect fluid “F”.

Although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure. 

What is claimed is:
 1. A system for subatmospheric pressure therapy comprising: a subatmospheric pressure mechanism comprising a housing and a vacuum source disposed within the housing; a collection bag fluidly connectable to a wound dressing and to the vacuum source, wherein the collection bag consists essentially of a gas-permeable material; a canister associated with the housing and wherein the collection bag is disposed within the canister; and a channel disposed at a wall of the canister, the channel in fluid communication with an interior cavity of the collection bag through the gas-permeable material.
 2. The system of claim 1, further comprising a check valve fluidly connecting the wound dressing and the interior cavity of the collection bag.
 3. A method of producing a subatmospheric pressure therapy system, comprising: providing a vacuum source; connecting a collection bag to the vacuum source, the collection bag consisting essentially of a gas-permeable material fluidly connectable to a wound dressing; and disposing the vacuum source within a housing and installing the collection bag in a canister, the canister associated with the housing, wherein the canister comprises a channel disposed at a wall of the canister, the channel in fluid communication with an interior cavity of the collection bag through the gas-permeable material.
 4. A negative pressure wound therapy system comprising: a negative pressure mechanism comprising a housing and a vacuum source disposed within the housing, the vacuum source configured to aspirate fluid from a wound; and a collection member configured to receive fluid from the wound and configured to be in fluidic communication with the vacuum source, the collection member comprising a cavity for receiving fluid and having an exterior portion when in use consisting essentially of a material capable of permitting any residual air or other gases to escape the cavity.
 5. The system of claim 4, wherein the collection member comprises an expandable cavity.
 6. The system of claim 4, wherein the collection member comprises an absorbent material configured to absorb and transfer wound fluid.
 7. The system of claim 4, wherein at least a part of the collection member comprises a transparent material.
 8. The system of claim 4, wherein the collection member comprises a liquid impermeable material.
 9. The system of claim 4, further comprising a wound contact layer configured to contact the wound.
 10. A method of providing negative pressure wound therapy to a wound, the method comprising: aspirating fluid from the wound using a negative pressure mechanism comprising a housing and a vacuum source disposed within the housing; and retaining the fluid aspirated from the wound in an interior cavity of a collection member, the collection member being in fluidic communication with the vacuum source, wherein the collection member has an exterior portion in use that consists essentially of a material that permits any residual air or other gases to escape the interior cavity.
 11. The system of claim 4, further comprising an inlet for receiving fluid from the wound into the collection member and an outlet configured to be in fluid communication to the vacuum source.
 12. The system of claim 4, further comprising a fluid conduit configured to provide fluid communication between the cavity of the collection member and the vacuum source.
 13. The system of claim 4, wherein the collection member comprises a hydrophobic material.
 14. The method of claim 10, wherein fluid is aspirated from the wound through a wound contact layer provided over the wound.
 15. The method of claim 10, wherein fluid aspirated from the wound is stored in an absorbent material.
 16. The method of claim 10, wherein fluid is aspirated from the wound through an inlet and into the collection member.
 17. The method of claim 10, comprising applying negative pressure to the wound through an outlet in fluid communication with the collection member.
 18. The method of claim 10, wherein the collection member comprises a hydrophobic material. 